1. Technical Field
The present invention relates to a high-speed search method for an LSP (Local Spectrum Pair) using SVQ (Split Vector Quantization) and a fixed codebook of the G.729 speech encoder, and more particularly to a high-speed search method which may decrease overall computational complexity without sacrificing spectral distortion performance by reducing a size of the codebook using an order character of LSP parameters in searching a codebook having high computational complexity during quantizing a split vector of LSP parameters of a speech encoder, used to compress voice signals in a low speed, and a high-speed search method which may dramatically reduce computational complexity without loss of tone quality by detecting and searching tracks on the basis of a magnitude order of a correlation signal (d′(n)), obtained by an impulse response and a target signal in the process of searching the fixed codebook of the G.729 speech encoder.
2. Description of the Prior Art
Generally, for the speech encoding in a less than 16 kbps transmission rate, the speech is not directly transmitted but parameters representing the speech are sampled and quantized to reduce magnitude of the data, in a circumstance that the bandwidth is limited.
For high-quality encoding, the low transmission speech encoder quantizes LPC coefficients, in which an optimal LPC coefficient is obtained by dividing the input speech signal in a frame unit to minimize predictive error energy in each frame.
LPC filter is commonly a 10th ALL-POLE filter.
In the above conventional method, more bits should be assigned to quantize the 10 LPC coefficients. However, when directly quantizing the LPC coefficients, there are problems that characters of the filters are very sensitive to the quantization error and that stability of the LPC filter is not assured after quantizing the coefficients.